With development trends of facilitation and miniaturization of wireless handheld devices, higher requirements are imposed on input configuration of the wireless handheld devices. As an input device that occupies small space and is convenient to use, a touchscreen is widely applied.
In a wireless handheld device having a touchscreen, physical coordinates of a touch on a screen are analyzed, and then a corresponding program is started or corresponding processing is performed. That is, a virtual keyboard or a menu is generally set in a touchscreen, and an operator generates touch input by touching or pressing a keyboard button on the virtual keyboard or a menu button on the menu.
However, in a practical application, in a dark ambient environment or in a case of emergency, a touchscreen user may fail to perform effective touch input on a wireless handheld device whose touchscreen is in a locked state; as a result, a related function cannot be operated in time, so that it is inconvenient to use.